Application - 3.2 | Chapter 2 : Ratio and Proportion | ICSE 8 Maths
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Application

3.2 - Application

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Understanding Ratios

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Teacher
Teacher Instructor

Today, we're going to discuss ratios! A ratio is a way to compare two quantities, and it's usually written in the form of 'a:b' or as a fraction 'a/b'. Can anyone give me an example of a ratio?

Student 1
Student 1

How about 3 boys to 4 girls, which can be written as 3:4?

Teacher
Teacher Instructor

Exactly! That's a great example. Remember, ratios help us understand relationships. When we look at equivalent ratios, they represent the same relationship despite having different numbers. For instance, 2:3 is equivalent to 4:6. Can you see how that works?

Student 2
Student 2

Yes! It's like scaling the numbers while keeping the relationship the same.

Teacher
Teacher Instructor

Right! Just like a recipe where you might double the ingredients but the ratio stays the same. That's what we mean by equivalence.

Proportions Explained

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Teacher
Teacher Instructor

Now let’s dive into proportions. A proportion states that two ratios are equal. Can anyone tell me how proportions work in daily life?

Student 3
Student 3

If we have more workers, we can finish a project faster, right? That’s a direct proportion!

Teacher
Teacher Instructor

Correct, Student_3! And what about instances where there's an inverse relationship?

Student 4
Student 4

Like if we increase our speed while driving, we can reduce the time it takes to reach our destination!

Teacher
Teacher Instructor

Fantastic! These real-world examples show how vital understanding proportions is for effective decision-making.

Unitary Method: Problem Solving

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Teacher
Teacher Instructor

Next, let’s explore the unitary method! This method helps us find the value of one unit to solve problems. Who can explain how we would use this method if we know that 5 books cost β‚Ή750?

Student 1
Student 1

We would first find the cost of one book, which is β‚Ή150.

Teacher
Teacher Instructor

Exactly! Now, how much would 8 books cost?

Student 2
Student 2

That’s β‚Ή1,200, since 8 multiplied by β‚Ή150 equals β‚Ή1,200!

Teacher
Teacher Instructor

Excellent work! The unitary method streamlines problem-solving by focusing on a single unit.

Percentage Applications

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Teacher
Teacher Instructor

Finally, let's talk about percentages, which are ratios that help us express a value out of 100. Who can provide us with the formula for calculating percentage?

Student 3
Student 3

It’s Percentage = (Part / Whole) Γ— 100.

Teacher
Teacher Instructor

Great! And can someone give me an example of where we see percentages in action?

Student 4
Student 4

Discounts in a store! If something costs β‚Ή1,000 and is on a 30% discount, we can calculate how much we save.

Teacher
Teacher Instructor

Exactly! Percentages are crucial for understanding finance, statistics, and even our grades in school!

Introduction & Overview

Read summaries of the section's main ideas at different levels of detail.

Quick Overview

This section discusses the application of ratios and proportions in various contexts, including problem solving and real-world scenarios.

Standard

The section highlights how ratios and proportions are fundamental in many aspects of mathematics and everyday situations, providing insights into various applications such as pricing, unitary methods, and percentage calculations.

Detailed

In this section, we explore the concepts of ratios and proportions, which are integral to understanding relationships between numbers. Ratios, expressed as a:b or a/b, allow us to compare quantities, while proportions establish the equality between two ratios. The key principle of the unitary method is introduced, demonstrating how to find the value of a single unit and scale it to the needed quantity. Additionally, percentages are covered as a specific type of ratio, with applications in financial scenarios like profit calculations and discounts. Furthermore, real-world applications are demonstrated through examples like cooking and chemistry, showcasing how these mathematical principles govern various processes and decisions. Ultimately, this section serves as a foundation for later mathematical concepts and everyday reasoning.

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Unitary Method Overview

Chapter 1 of 2

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Chapter Content

Problem-Solving Steps
1. Find value for 1 unit
2. Scale to required quantity

Detailed Explanation

The unitary method is a technique used to solve problems related to ratios and proportions. The first step is to find the value of a single unit by dividing the total quantity by the number of units available. For example, if you have the total cost for multiple items, you divide that cost by the number of items to find the cost of one item. The second step is to scale this value to find the total cost or value of the required number of items or units. This is done by multiplying the cost of one unit by the targeted number of units.

Examples & Analogies

Imagine you are at a store where you want to know how much one chocolate bar costs if the store has a pack of 5 bars for β‚Ή250. By using the unitary method, you divide β‚Ή250 by 5 to find the cost of one chocolate bar, which is β‚Ή50. If you want to buy 3 chocolate bars, you simply multiply β‚Ή50 by 3 to find out that it will cost you β‚Ή150.

Practical Application Example

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Chapter Content

Application:
If 5 books cost β‚Ή750:
1 book = β‚Ή750/5 = β‚Ή150
8 books = 8 Γ— β‚Ή150 = β‚Ή1,200

Detailed Explanation

This example illustrates how the unitary method can be applied in a real-life scenario. First, we calculate the cost of one book by dividing the total cost (β‚Ή750) by the number of books (5), which gives us β‚Ή150 for one book. Next, if you want to find out the cost of 8 books, you multiply the cost of one book (β‚Ή150) by 8. Thus, 8 books will cost β‚Ή1,200. This systematic process of breaking down the problem helps you understand how to scale quantities effectively.

Examples & Analogies

Consider wanting to buy a set of 5 pencils for β‚Ή75. To find out how much one pencil costs, you divide β‚Ή75 by 5, resulting in β‚Ή15. If you decide to buy 10 pencils, you can use the unitary method again: multiply β‚Ή15 by 10 to figure out it's β‚Ή150 for 10 pencils. This demonstrates a practical application of the unitary method in everyday purchases.

Key Concepts

  • Ratio: A way to compare two quantities, expressed as a:b.

  • Proportion: An equality between two ratios, crucial for understanding relationships.

  • Equivalent Ratios: Different representations of the same ratio.

  • Unitary Method: A technique to find the value of one unit for solving problems.

  • Percentage: A ratio expressed per hundred, often used in financial calculations.

Examples & Applications

If there are 2 boys for every 3 girls, the ratio is 2:3.

In a recipe, if the quantities are doubled, the equivalent ratios maintain the same relationship.

If a 30% discount is applied to an item of β‚Ή1,000, the sale price is β‚Ή700.

Memory Aids

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Rhymes

To compare is a ratio’s goal, keeping numbers in control.

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Stories

Imagine a baker who uses 2 cups of sugar for every 5 cups of flour. This recipe relies on ratios, showing how essential they are in cooking!

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Memory Tools

RAP helps you remember: R for Ratio, A for Application, P for Proportion.

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Acronyms

RASP - Ratios, Application, Simplest form, Percentage.

Flash Cards

Glossary

Ratio

A comparison of two quantities expressed as a:b.

Proportion

An equality between two ratios.

Equivalent Ratios

Different ratios that express the same relationship.

Unitary Method

A way to find the value of a single unit to solve problems.

Percentage

A ratio expressed as a fraction of 100.

Reference links

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